单项选择题

A.骨折平面至肢体远端的2倍
B.骨折平面至肢体远端的2倍加10cm
C.骨折平面至肢体远端的2倍加20cm
D.骨折平面至肢体远端的2倍加30cm
E.骨折平面至肢体远端的2倍加40cm